Cluster of differentiation 10 (CD10) is also known as membrane metallo-endopeptidase, neutral endopeptidase (NEP), Neprilysin, and common acute lymphoblastic leukemia antigen (CALLA), is a 90-110-kDa type II transmembrane glycoprotein normally expressed by a variety of tissues, including epithelial cells of the prostate, kidney, intestine, endometrium, adrenal glands, and lung. This zinc-dependent metalloprotease enzyme cleaves peptide bonds on the amino side of hydrophobic residues and inactivates a variety of physiologically active secreted peptides. CD20 is thought to be the rate-limiting degrading enzyme of amyloid β peptide (Aβ) whose abnormal misfolding and aggregation in neural tissue has been implicated in the development of Alzheimer's disease (AD). CD10 is also identified as the common acute lymphoblastic leukemia antigen (CALLA) present on leukemic cells of pre-B phenotype, and thus serves as the most important biomarker in the diagnosis of human acute lymphocytic leukemia (ALL).